The Web of Science ranking of the world’s most highly-cited scientists was released this morning, telling us who makes up the top 1 percent of the world’s scientists. These are the authors of influential papers that other scientists point to when making their arguments.
EDITOR’S NOTE! — Web of Science shared last year’s data! We apologize. List below is now corrected, changes to copy in bold. We’re so sorry.
Twenty-three of the citation laureates are Duke scholars or had a Duke affiliation when the landmark works were created over the last decade.
A couple of these Duke people disappeared from this year’s list, but we’re still proud of them.
Dan Scolnic of Physics returns as our lone entry in Space Science, which just makes Duke sound cooler all around, don’t you think?
This is a big deal for the named faculty and an impressive line on their CVs. But the selection process weeds out “hyper-authorship, excessive self-citation and anomalous citation patterns,” so don’t even think about gaming it.
Fifty-nine nations are represented by the 6,636 individual researchers on this year’s list. About half of the citation champions are in specific fields and half in ‘cross-field’ — where interdisciplinary Duke typically dominates. The U.S. is still the most-cited nation with 36 percent of the world’s share, but shrinking slightly. Mainland China continues to rise, claiming second place with 20 percent of the cohort, up 2.5 percent from just last year. Then, in order, the UK, Germany and Australia round out the top five.
In fact, five Duke NUS faculty made this year’s list: Antonio Bertoletti, Derek Hausenloy and Jenny Guek-Hong Low for cross-field; Carolyn S. P. Lam for clinical medicine, and the world famous “Bat Man,” Lin-Fa Wang, for microbiology.
In some parts of the world, animals are going extinct before scientists can even name them.
Such may be the case for mouse lemurs, the saucer-eyed, teacup-sized primates native to the African island of Madagascar.
Various species of mouse lemurs found in Madagascar. Photos by Sam Hyde Roberts
There, deforestation has prompted the International Union for the Conservation of Nature (IUCN) to classify some of these tree-dwelling cousins as “endangered” even before they are formally described.
Duke professor Anne Yoder has been trying to take stock of how many mouse lemur species are alive today before they blink out of existence.
It’s not an easy task. Mouse lemurs are shy, they only come out at night, and they live in hard-to-reach places in remote forests. To add to the difficulty, many species of mouse lemurs are essentially lookalikes. It’s impossible to tell them apart just by peering at them through binoculars.
When Yoder first started studying mouse lemurs some 25 years ago, there were only three distinct species recognized by scientists. Over time and with advances in DNA sequencing, researchers began to wonder if what looked like three species might actually be upwards of two dozen.
In a new study, Yoder and dozens of colleagues from Europe, Madagascar and North America compiled and analyzed 50 years of hard-won data on the physical, behavioral and genetic differences among mouse lemurs to try to pin down the true number.
While many mouse lemur species look alike, they have different diets, and males use different calls to find and woo their mates, the researchers explain.
By pinning down their number and location, researchers hope to make more informed decisions about how best to help keep these species from the brink.
The study was published Sept. 27 in the journal Nature Ecology & Evolution.
Braxton Craven Distinguished Professor of Evolutionary Biology, Anne Yoder was director of the Duke Lemur Center from 2006 to 2018.
At 12 years old, I scribbled in my brand new pink notebook, covered in owls. I dubbed it my “question notebook,” filled with about twenty other easily-googleable questions. “A blueprint to our bodies,” was the result of my first internet search for the definition of a gene. But this blueprint had failed so many, even my own grandfather. Could it fail me down the road? Could I one day find an explanation?
By 16, I had been steadfast for years in my decision to pursue medicine. But, on the other side of perseverance is tunnel-vision. At Lyons Township High School in Western Springs, Illinois, I refused to stray the path I had meticulously designed for myself. I confined myself to chemistry, math, and biology. I bounded my limits to only APs, and only extracurriculars that “made sense.”
Perhaps the only time I strayed from the path was by pursuing competitive gymnastics until I graduated, despite 20-hour weeks and numerous insistences from my parents to quit. I was determined to keep something that did not belong to my future.
It wasn’t until class selection for my first Duke semester that I allowed myself to magnify this idea of straying from my path. I wasn’t loading up my schedule with Organic Chemistry or Physics, seeking to check off requirements for the MCAT. Instead, I was selecting Computer Science 101.
Upon beginning my new life at Duke, I felt a strange taste in my mouth whenever I was asked what I was studying. I was no longer “pre-med.” My years spent taking rigorous STEM classes and conducting independent research projects felt like a waste. I wasn’t even a gymnast anymore.
Two huge pieces of my identity had been excised, leaving gaping holes that I felt clueless at how to fill.
Sophomore year, I have been seeking out more ways in which I can stray. In pursuit of the elusive software engineering internship, I felt myself settling into a familiar mindset of: “What is most practical?” I refuse to enter this rut again. So, I enrolled in film editing, a class that has long-since sparked my interest.
I love the quote: “the best ideas are the most disruptive.” This summer, I fell in love with hiking, the solitude enveloping me in a cocoon of my wildest ideas. Alone, I can craft a business idea, or conceive an unusual plot for a movie. I can weave together the bits and pieces of my imagination.
I was drawn to film editing because of the analogy that the editor clears a path in a forest. With so many directions to go, they are responsible for compelling emotion out of the audience. I’ve found that a disruptive idea will do the same.
My draw to the Duke Research Blog stemmed from two places. First, I wanted to continue to stray from my path by re-exploring my childhood love for writing. Second, I craved time to learn about other’s disruptive ideas, in hopes of getting inspiration for some of my own.
Geer Cemetary in Durham is one of many burial grounds in America that hold the remains of thousands of Black Americans from the 19th century. There are no records of the people buried there. The process of researching grounds like these as a form of reparations to descendent communities was pioneered by Michael Blakey in the African Burial Ground Project in Lower Manhattan, New York. He is currently the Director of the Institute for Historical Biology at the College of William and Mary.
On April 4, Blakey visited Duke as a guest of the Franklin Institute of Humanities, the Department of Classical Studies, the Department of International Comparative Studies, and Trinity College. In attendance to his lecture were students of Classical Studies 144: Principles of Archaeology with Alicia Jimenez, International Comparative Studies 283: Death, Burial, and Justice in the Americas with Adam Rosenblatt, and several graduate students by invitation (and me). His presence was clearly highly anticipated.
I initially approached Dr. Jimenez with my interest in bioarchaeology in January as I was planning my Program II application. She invited me to this seminar, and to lunch with Blakey and the graduate students beforehand. I came prepped with questions on osteopenia and hypertrophy, as well as a map of Brightleaf Square so I wouldn’t get lost (I still got lost) and a few dollars cash for parking (they only took card).
For those of you who have ever loved the detective fiction heroine Temperance Brennan, Blakey’s work is for you. He is co-chair of the Commission for the Ethical Treatment of Human Remains through the American Anthropological Association. He was claiming the title of bioanthropologist before it was cool. He wrote a guide for the profession called Engaging Descendant Communities, or, more lovingly, The Rubric. Blakey encourages allowing those descendant communities to guide scientists’ research on human remains. He calls us Homo reminiscens, because what makes us “human” may be our affinity for memorializing our dead as much as it may be our large brains (á la Homo sapiens). “Burial is human dignity,” Blakey announced during the seminar, “Dignity is what we do.”
“Ethical code is not law. It is our greatest responsibility.”
Michael Blakey
After all, science has historically been used to justify the unjust. Bioarchaeology is a famous contributor to the field; the pseudoscience of phrenology was upheld until well into the 20th century, and was originally used as “scientific proof” that people of African descent were lesser than Europeans. It was also cited as a justification for displacing Native Americans from their lands.
During lunch, I was struck by Blakey’s cadence. He had a deep, slow voice and spoke with intention. He ordered the giant pretzel. I never asked my questions; instead, I was swept away by the group’s discussion on ethics–a topic I had no open Safari tabs on. I asked instead why a scientist would choose to guide themselves entirely by a non-expert opinion rather than scientific inquiry; would that not hinder discovery?
The scientific method, as you may recall, starts with asking a question. Rather than gracefully including descendent communities after the paper has been written, Blakey urges scientists to only pursue questions about remains that the descendants wish to answer. The science of death should never be self-serving, he noted. There is no purpose to publishing a paper if it is not in the service of the community that provided the subject. A critical reader may notice that The Rubric is not called The Gospel or The Constitution. Rather than a rule of law, it is a guideline. That’s because ethics is based on the respect of self, of craft, and of others. “Ethical code is not law,” Blakey reminds scientists. “It is our greatest responsibility.”
Geer Cemetary has been the subject of Duke research for years now, from a Story+ program to class field trips. Members of ICS, CLST, and FHHI have been in cooperation with Friends of Geer Cemetary to answer such questions about burial conditions–the attempt at dignity granted to Black residents of Durham by their descendants.
Edit: a previous version of this article had incorrectly stated that the Department of African and African American Studies sponsored Michael Blakey’s lecture.
If you’re a doe-eyed first-year at Duke who wants to eventually become a doctor, chances are you are currently, or will soon, take part in a pre-med rite of passage: finding a lab to research in.
Most pre-meds find themselves researching in the fields of biology, chemistry, or neuroscience, with many hoping to make research a part of their future careers as clinicians. Undergraduate student and San Diego native Eden Deng (T’23) also found herself plodding a similar path in a neuroimaging lab her freshman year.
Eden Deng T’23
At the time, she was a prospective neuroscience major on the pre-med track. But as she soon realized, neuroimaging is done through fMRI. And to analyze fMRI data, you need to be able to conduct data analysis.
This initial research experience at Duke in the Martucci Lab, which looks at chronic pain and the role of the central nervous system, sparked a realization for Deng. “Ninety percent of my time was spent thinking about computational and statistical problems,” she explained to me. Analysis was new to her, and as she found herself struggling with it, she thought to herself, “why don’t I spend more time getting better at that academically?”
Deng at the Martucci Lab
This desire to get better at research led Deng to pursue a major in Statistics with a secondary in Computer Science, while still on the pre-med track. Many people might instantly think about how hard it must be to fit in so much challenging coursework that has virtually no overlap. And as Deng confirmed, her academic path not been without challenges.
For one, she’s never really liked math, so she was wary of getting into computation. Additionally, considering that most Statistics and Computer Science students want to pursue jobs in the technology industry, it’s been hard for her to connect with like-minded people who are equally familiar with computers and the human body.
“I never felt like I excelled in my classes,” Deng said. “And that was never my intention.” Deng had to quickly get used to facing what she didn’t know head-on. But as she kept her head down, put in the work, and trusted that eventually she would figure things out, the merits of her unconventional academic path started to become more apparent.
Research at the intersection of data and health
Last summer, Deng landed a summer research experience at Mount Sinai, where she looked at patient-level cancer data. Utilizing her knowledge in both biology and data analytics, she worked on a computational screener that scientists and biologists could use to measure gene expression in diseased versus normal cells. This will ultimately aid efforts in narrowing down the best genes to target in drug development. Deng will be back at Mount Sinai full-time after graduation, to continue her research before applying to medical school.
Deng presenting on her research at Mount Sinai
But in her own words, Deng’s most favorite research experience has been her senior thesis through Duke’s Department of Biostatistics and Bioinformatics. Last year, she reached out to Dr. Xiaofei Wang, who is part of a team conducting a randomized controlled trial to compare the merits of two different lung tumor treatments.
Generally, when faced with lung disease, the conservative approach is to remove the whole lobe. But that can pose challenges to the quality of life of people who are older, with more comorbidities. Recently, there has been a push to focus on removing smaller sections of lung tissue instead. Deng’s thesis looks at patient surgical data over the past 15 years, showing that patient survival rates have improved as more of these segmentectomies – or smaller sections of tissue removal – have become more frequent in select groups of patients.
“I really enjoy working on it every week,” Deng says about her thesis, “which is not something I can usually say about most of the work I do!” According to Deng, a lot of research – hers included – is derived from researchers mulling over what they think would be interesting to look at in a silo, without considering what problems might be most useful for society at large. What’s valuable for Deng about her thesis work is that she’s gotten to work closely with not just statisticians but thoracic surgeons. “Originally my thesis was going to go in a different direction,” she said, but upon consulting with surgeons who directly impacted the data she was using – and would be directly impacted by her results – she changed her research question.
The merits of an interdisciplinary academic path
Deng’s unique path makes her the perfect person to ask: is pursuing seemingly disparate interests, like being a Statistics and Computer Science double-major on the pre-med, track worth it? And judging by Deng’s insights, the answer is a resounding yes.
At Duke, she says, “I’ve been challenged by many things that I wouldn’t have expected to be able to do myself” – like dealing with the catch-up work of switching majors and pursuing independent research. But over time she’s learned that even if something seems daunting in the moment, if you apply yourself, most, if not all things, can be accomplished. And she’s grateful for the confidence that she’s acquired through pursuing her unique path.
Moreover, as Deng reflects on where she sees herself – and the field of healthcare – a few years from now, she muses that for the first time in the history of healthcare, a third-party player is joining the mix – technology.
While her initial motivation to pursue statistics and computer science was to aid her in research, “I’ve now seen how its beneficial for my long-term goals of going to med school and becoming a physician.” As healthcare evolves and the introduction of algorithms, AI and other technological advancements widens the gap between traditional and contemporary medicine, Deng hopes to deconstruct it all and make healthcare technology more accessible to patients and providers.
“At the end of the day, it’s data that doctors are communicating to patients,” Deng says. So she’s grateful to have gained experience interpreting and modeling data at Duke through her academic coursework.
And as the Statistics major particularly has taught her, complexity is not always a good thing – sometimes, the simpler you can make something, the better. “Some research doesn’t always do this,” she says – she’s encountered her fair share of research that feels performative, prioritizing complexity to appear more intellectual. But by continually asking herself whether her research is explainable and applicable, she hopes to let those two questions be the North Stars that guide her future research endeavors.
At the end of the day, it’s data that doctors are communicating to patients.
Eden Deng
When asked what advice she has for first-years, Deng said that it’s important “to not let your inexperience or perceived lack of knowledge prevent you from diving into what interests you.” Even as a first-year undergrad, know that you can contribute to academia and the world of research.
And for those who might be interested in pursuing an academic path like Deng, there’s some good news. After Deng talked to the Statistics department about the lack of pre-health representation that existed, the Statistics department now has a pre-health listserv that you can join for updates and opportunities pertaining specifically to pre-med Stats majors. And Deng emphasizes that the Stats-CS-pre-med group at Duke is growing. She’s noticed quite a few underclassmen in the Statistics and Computer Science departments who vocalize an interest in medical school.
So if you also want to hone your ability to communicate research that you care about – whether you’re pre-med or not – feel free to jump right into the world of data analysis. As Deng concludes, “everyone has something to say that’s important.”
Chances are, you have not felt betrayed by a Google form. But if you’re part of the 8% of multiracial students at Duke, perhaps you’re familiar.
If you check one box, it feels like you deny your identity as another. It is a constant battle of representation, of feeling a responsibility towards all of your communities while simultaneously feeling an imposter in all of them. There is always the issue of being too white for one group, too brown for another.
Since 2012, every county in the United States has reported a multiracial population. Dr. Sarah Gaither, an assistant professor of psychology & neuroscience at Duke, studies the identity crisis multiracial students face. In 2015, she published “‘Mixed’ Results: Multiracial Research and Identity Explorations” in Current Directions in Psychological Science. And on February 10, she organized a screening of MIXED, a documentary following the struggles and backlash facing mixed-race families. The film’s directors, Caty Borum and Leena Jayaswal of American University, joined the screening and provided a Q&A session for the audience.
Image courtesy of Dan Vahaba
Gaither’s research is featured in the film, as well as Duke SWIRL (Students With Interracial Legacies), a former student organization.
“Multiracials who identify as multiracial actually experience decreased self-esteem when asked to choose only one racial identity,” Gaither notes in her article. Sure enough, the documentary follows America’s slow response to progress. Despite being in the aftermath of our first biracial president, despite it being over 50 years since Loving v. Virginia, which legalized interracial marriage nationwide, there have only been two U.S. Censuses taken since the Census Bureau allowed more than one race to be checked on official forms. This caused a notable shift; between 2000 and 2010, the number of reported interracial people increased by 32%, likely because of the ability to “claim more than one race” as a legal identity.
Duke’s Undergraduate Student Body, Fall 2022 (Source: https://facts.duke.edu/)
Gaither’s research in the Duke Identity and Diversity Lab pledges to continue this research. She notes interesting extensions of multiracial identities, such as Latinx students and families who are subject to even more confusing checkboxes on aforementioned Google forms (What is your race and ethnicity? Because “Hispanic/Latino” is its own category).
“The process of racial self-identification can be more challenging as racial categories can be complex and/or ambiguous,” Gaither says. She also notes the identity crises genderqueer people face, and how restricting checkboxes can really be.
Image courtesy of Dan Vahaba
The documentary provides the viewer an opportunity to experience the inequities and bigotries that still exist toward multiracial families. Race, after all, is genetically irrelevant. The documentary team gives examples of questions they are often asked:
“Are you the nanny?” “What is she?” “Did you adopt those children?” “Where did they come from?”
And I’ll add a few more, from experience:
“It’ll be two separate checks today?” “Where do you get that hair from?” “Is this your aunt?”
The point is: racial divides are projected by outsiders onto mixed families, and it creates a crisis of identity for mixed-race individuals. It is a phenomenon well documented by Gaither, Borum, Jayaswal, and others who have lived it.
Processed foods and overuse of antibiotics can wreak havoc on the trillions of bacteria and other microbes that inhabit the gut. A new study of the gut microbiomes of lemurs looks at whether reconnecting with nature can help restore this internal ecosystem to a more natural state. Credit: Sally Bornbusch.
Modern life messes with the microbiome -– the trillions of bacteria and other microbes that live inside the body. Could reconnecting with nature bring this internal ecosystem back into balance?
A new study suggests it can, at least in lemurs. Led by Duke Ph.D. alumnus Sally Bornbusch and her graduate advisor Christine Drea, the research team collected fecal samples from more than 170 ring-tailed lemurs living in various conditions in Madagascar: some were living in the wild, some were kept as pets, and some were rescued from the pet and tourism industries and then relocated to a rescue center in southwestern Madagascar where they ate a more natural diet and had less exposure to people.
Collecting fecal samples in Madagascar
Then the researchers sequenced DNA from the fecal samples to identify their microbial makeup. They found that the longer lemurs lived at the rescue center, the more similar their gut microbes were to those of their wild counterparts. Former pet lemurs with more time at the rescue center also showed fewer signs of antibiotic resistance.
By “rewilding” the guts of captive animals, researchers say we may be able to better prime them for success, whether after rescue or before translocation or reintroduction into the wild.
This research was supported by grants from the National Science Foundation (1945776, 1749465), the Triangle Center for Evolutionary Medicine, Duke’s Kenan Institute for Ethics, the Margot Marsh Biodiversity Fund and Lemur Love.
CITATION: “Microbial Rewilding in the Gut Microbiomes of Captive Ring-Tailed Lemurs (Lemur catta) in Madagascar,” Sally L. Bornbusch, Tara A. Clarke, Sylvia Hobilalaina, Honore Soatata Reseva, Marni LaFleur & Christine M. Drea. Scientific Reports, Dec. 27, 2022. DOI: 10.1038/s41598-022-26861-0.
Jake, a German shepherd dog in a Bailey chair. Dogs with megaesophagus must eat in a vertical position to help food travel to their stomachs. Photo credit: Beth Grant
Some dogs have to eat in a high chair—or, more specifically, a Bailey Chair. The chair keeps them in a vertical position while they eat so that gravity can do the work their bodies can’t: moving food from the mouth to the stomach.
These dogs have megaesophagus, an esophagus disorder that can prevent dogs from properly digesting food and absorbing nutrients. When you swallow a bite of food, it travels down a muscular tube, the esophagus, to the stomach. In humans, the esophagus is vertical, so our esophageal muscles don’t have to fight against gravity. But because dogs are quadrupeds, a dog’s esophagus is more horizontal, so “there is a greater burden on peristaltic contractions to transport the food into the stomach.” In dogs with megaesophagus, the esophagus is dilated, and those contractions are less effective. Instead of moving properly into the stomach, food can remain in the esophagus, exacerbating the problem and preventing proper digestion and nutrient absorption.
Leigh Anne Clark, Ph.D., an associate professor at Clemson University, recently spoke at Duke about megaesophagus in dogs and its genetic underpinnings. She has authored dozens of publications on dog genetics, including five cover features. Her research primarily involves “[mapping] alleles and genes that underlie disease in dogs.” In complex diseases like megaesophagus, that’s easier said than done. “This disease has a spectrum,” Clark says, and “Spoiler: that makes it more complicated to map.”
Clinical signs of megaesophagus, or mega for short, include regurgitation, coughing, loss of appetite, and weight loss. (We might use the word “symptom” to talk about human conditions, but “a symptom is something someone describes—e.g., I feel nauseous. But dogs can’t talk, so we can only see ‘clinical signs.’”) Complications of mega can include aspiration pneumonia and, in severe cases, gastroesophageal intussusception, an emergency situation in which dogs “suck their stomach up into their esophagus.”
Leigh Anne Clark of Clemson University
Sometimes megaesophagus resolves on its own with age, but when it doesn’t it requires lifelong management. Mega has no cure, but management can involve vertical feeding, smaller and more frequent meals, soft foods, and sometimes medication. Even liquid water can cause problems, so some dogs with mega receive “cubed water,” made by adding a “gelatinous material” to water, instead of a normal water bowl.
In dogs, mega can be either congenital, meaning present at birth, or acquired. In cases of acquired megaesophagus, the condition is “usually secondary to something else,” and the root cause is often never determined. (Humans can get mega, too, but as with acquired mega in dogs, mega in humans is usually caused by a preexisting condition. The best human comparison, according to Clark, might be achalasia, a rare disorder that causes difficulty swallowing.) Clark’s current research focuses on the congenital form of the disease in dogs.
Her laboratory recently published a paper investigating the genetic foundation of mega. Unlike some diseases, mega isn’t caused by just one genetic mutation, so determining what genes might be at play required some genetic detective work. “You see mega across breeds,” Clark says, which suggests an environmental component, but the disease is more prevalent in some breeds than others. For instance, 28 percent of all diagnoses are in German shepherds. That was a “red flag” indicating that genes were at least partly responsible.
Clark and her collaborators chose to limit their research study to German shepherds. Despite including a wide range of dogs in the study, they noticed that males were significantly overrepresented. Clark thinks that estrogen, a hormone more abundant in females, may have a protective effect against mega.
Clark and her team performed a genome-wide association study (GWAS) to look for alleles that are more common in dogs with mega. One allele that turned out to be a major risk factor was a variant of the MCHR2 gene, which plays a role in feeding behaviors. In breeds where mega is overrepresented, like German shepherds, “we have a situation where the predominant allele in the population is also the risk allele,” says Clark.
Using the results of the study, they developed a test that can identify which version of the gene a given dog has. The test, available at veterinary testing companies, is designed “to help breeders reduce the frequency of the risk allele and to plan matings that are less likely to produce affected puppies.”
Saxicolous lichens (lichens that grow on stones) from the Namib Desert, and finger lichen, Dactylina arctica (bottom left insert), common in the Arctic, on display in Dr. Jolanta Miadlikowska’s office. The orange color on some of the lichen comes from metabolites, or secondary chemicals produced by different lichen species. The finger lichen is hollow.
Lichens are everywhere—grayish-green patches on tree bark on the Duke campus, rough orange crusts on desert rocks, even in the Antarctic tundra. They are “pioneer species,” often the first living things to return to barren, desolate places after an extreme disturbance like a lava flow. They can withstand extreme conditions and survive where nearly nothing else can. But what exactly are lichens, and why does Duke have 160,000 of them in little envelopes? I reached out to Dr. Jolanta Miadlikowska and Dr. Scott LaGreca, two lichen researchers at Duke, to learn more.
Dr. Jolanta Miadlikowska looking at lichen specimens under a dissecting microscope. The pale, stringy lichen on the brown bag is whiteworm lichen (Thamnolia vermicularis), used to make “snow tea” in parts of China.
According to Miadlikowska, a senior researcher, lab manager, and lichenologist in the Lutzoni Lab (and one of the Instructors B for the Bio201 Gateway course) at Duke, lichens are “obligate symbiotic associations,” meaning they are composed of two or more organisms that need each other. All lichens represent a symbiotic relationship between a fungus (the “mycobiont”) and either an alga or a cyanobacterium or both (the “photobiont”). They aren’t just cohabiting; they rely on each other for survival. The mycobiont builds the thallus, which gives lichen its structure. The photobiont, on the other hand, isn’t visible—but it is important: it provides “food” for the lichen and can sometimes affect the lichen’s color. The name of a lichen species refers to its fungal partner, whereas the photobiont has its own name.
Lichen viewed through a dissecting microscope. The black speckles visible on some of the orange lichen lobes are a “lichenicolous” fungus that can grow on top of lichen. There are also “endolichenic fungi… very complex fungal communities that live inside lichen,” Miadlikowska says. “We don’t see them, but they are there. And they are very interesting.”
Unlike plants, fungi can’t perform photosynthesis, so they have to find other ways to feed themselves. Many fungi, like mushrooms and bread mold, are saprotrophs, meaning they get nutrients from organic matter in their environment. (The word “saprotroph” comes from Greek and literally means “rotten nourishment.”) But the fungi in lichens, Miadlikowska says, “found another way of getting the sugar—because it’s all about the sugar—by associating with an organism that can do photosynthesis.” More often than not, that organism is a type of green algae, but it can also be a photosynthetic bacterium (cyanobacteria, also called blue-green algae). It is still unclear how the mycobiont finds the matching photobiont if both partners are not dispersed together. Maybe the fungal spores (very small fungal reproductive unit) “will just sit and wait” until the right photobiont partner comes along. (How romantic.) Some mycobionts are specialists that “can only associate with a few or a single partner—a ‘species’ of Nostoc [a cyanobacterium; we still don’t know how many species of symbiotic and free-living Nostoc are out there and how to recognize them], for example,” but many are generalists with more flexible preferences.
Two species of foliose (leaf-like) lichens from the genus Peltigera. In the species on the left (P. canina), the only photobiont is a cyanobacterium from the genus Nostoc, making it an example of bi-membered symbiosis. In the species on the right (P.aphthosa), on the other hand, the primary photobiont is a green alga (which is why the thallus is so green when wet). In this case, Nostoc is a secondary photobiont contained only in the cephalodia—the dark, wart-like structures on the surface. With two photobionts plus the mycobiont, this is an example of tri-membered symbiosis.
Lichens are classified based on their overall thallus shape. They can be foliose (leaf-like), fruticose (shrubby), or crustose (forming a crust on rocks or other surfaces). Lichens that grow on trees are epiphytic, while those that live on rocks are saxicolous; lichens that live on top of mosses are muscicolous, and ground-dwelling lichens are terricolous. Much of Miadlikowska’s research is on a group of cyanolichens (lichens with cyanobacteria partners) from the genus Peltigera. She works on the systematics and evolution of this group using morphology-, anatomy-, and chemistry-based methods and molecular phylogenetic tools. She is also part of a team exploring biodiversity, ecological rules, and biogeographical patterns in cryptic fungal communities associated with lichens and plants (endolichenic and endophytic fungi). She has been involved in multiple ongoing NSF-funded projects and also helping graduate students Ian, Carlos, Shannon, and Diego in their dissertation research. She spent last summer collecting lichens with Carlos and Shannon and collaborators in Alberta, Canada and Alaska. If you walk in the sub basement of the Bio Sciences building where Bio201 and Bio202 labs are located, check out the amazing photos of lichens (taken by Thomas Barlow, former Duke undergraduate) displayed along the walls! Notice Peltigera species, including some new to science, described by the Duke lichen team.
Lichens have value beyond the realm of research, too. “In traditional medicine, lichens have a lot of use,” Miadlikowska says. Aside from medicinal uses, they have also been used to dye fabric and kill wolves. Some are edible. Miadlikowska herself has eaten them several times. She had salad in China that was made with leafy lichens (the taste, she says, came mostly from soy sauce and rice vinegar, but “the texture was coming from the lichen.”). In Quebec, she drank tea made with native plants and lichens, and in Scandinavia, she tried candied Cetraria islandica lichen (she mostly tasted the sugar and a bit of bitterness, but once again, the lichen’s texture was apparent).
In today’s changing world, lichens have another use as well, as “bioindicators to monitor the quality of the air.” Most lichens can’t tolerate air pollution, which is why “in big cities… when you look at the trees, there are almost no lichens. The bark is just naked.” Lichen-covered trees, then, can be a very good sign, though the type of lichen matters, too. “The most sensitive lichens are the shrubby ones… like Usnea,” Miadlikowska says. Some lichens, on the other hand, “are able to survive in anthropogenic places, and they just take over.” Even on “artificial substrates like concrete, you often see lichens.” Along with being very sensitive to poor air quality, lichens also accumulate pollutants, which makes them useful for monitoring deposition of metals and radioactive materials in the environment.
Dr. Scott LaGreca with some of the 160,000 lichen specimens in Duke’s herbarium.
LaGreca, like Miadlikoska, is a lichenologist. His research primarily concerns systematics, evolution and chemistry of the genus Ramalina. He’s particularly interested in “species-level relationships.” While he specializes in lichens now, LaGreca was a botany major in college. He’d always been interested in plants, in part because they’re so different from animals—a whole different “way of being,” as he puts it. He used to take himself on botany walks in high school, and he never lost his passion for learning the names of different species. “Everything has a name,” he says. “Everything out there has a name.” Those names aren’t always well-known. “Some people are plant-blind, as they call it…. They don’t know maples from oaks.” In college he also became interested in other organisms traditionally studied by botanists—like fungi. When he took a class on fungi, he became intrigued by lichens he saw on field trips. His professor was more interested in mushrooms, but LaGreca wanted to learn more, so he specialized in lichens during grad school at Duke, and now lichens are central to his job. He researches them, offers help with identification to other scientists, and is the collections manager for the lichens in the W.L. and C.F. Culberson Lichen Herbarium—all 160,000 of them.
The Duke Herbarium was founded in 1921 by Dr. Hugo Blomquist. It contains more than 825,000 specimens of vascular and nonvascular plants, algae, fungi, and, of course, lichens. Some of those specimens are “type” specimens, meaning they represent species new to science. A type specimen essentially becomes the prototype for its species and “the ultimate arbiter of whether something is species X or not.” But how are lichens identified, anyway?
Lichenologists can consider morphology, habitat, and other traits, but thanks to Dr. Chicita Culberson, who was a chemist and adjunct professor at Duke before her retirement, they have another crucial tool available as well. Culbertson created a game-changing technique to identify lichens using their chemicals, or metabolites, which are often species-specific and thus diagnostic for identification purposes. That technique, still used over fifty years later, is a form of thin-layer chromatography. The process, as LaGreca explains, involves putting extracts from lichen specimens—both the specimens you’re trying to identify and “controls,” or known samples of probable species matches—on silica-backed glass plates. The plates are then immersed in solvents, and the chemicals in the lichens travel up the paper. After the plates have dried, you can look at them under UV light to see if any spots are fluorescing. Then you spray the plates with acid and “bake it for a couple hours.” By the end of the process, the spots of lichen chemicals should be visible even without UV light. If a lichen sample has traveled the same distance up the paper as the control specimen, and if it has a similar color, it’s a match. If not, you can repeat the process with other possible matches until you establish your specimen’s chemistry and, from there, its identity. Culberson’s method helped standardize lichen identification. Her husband also worked with lichens and was a director of the Duke Gardens.
Thin-layer chromatography plates in Dr. LaGreca’s office. The technique, created by Dr. Chicita Culberson, helps scientists identify lichens by comparing their chemical composition to samples of known identity. Each plate was spotted with extracts from different lichen specimens, and then each was immersed in a different solvent, after which the chemicals in the extracts travel up the plate . Each lichen chemical travels a characteristic distance (called the “Rf value”) in each solvent. Here, the sample in column 1 on the rightmost panel matches the control sample in column 2 in terms of distance traveled up the page, indicating that they’re the same species. The sample in column 4, on the other hand, didn’t travel as far as the one in column 5 and has a different color. Therefore, those chemicals (and species) do not match.
LaGreca shows me a workroom devoted to organisms that are cryptogamic, a word meaning “hidden gametes, or hidden sex.” It’s a catch-all term for non-flowering organisms that “zoologists didn’t want to study,” like non-flowering plants, algae, and fungi. It’s here that new lichen samples are processed. The walls of the workroom are adorned with brightly colored lichen posters, plus an ominous sign warning that “Unattended children will be given an espresso and a free puppy.” Tucked away on a shelf, hiding between binders of official-looking documents, is a thin science fiction novel called “Trouble with Lichen” by John Wyndham.
The Culberson Lichen Herbarium itself is a large room lined with rows of cabinets filled with stacks upon stacks of folders and boxes of meticulously organized lichen samples. A few shelves are devoted to lichen-themed books with titles like Lichens De France and Natural History of the Danish Lichens.
Each lichen specimen is stored in an archival (acid-free) paper packet, with a label that says who collected it, where, and on what date. (“They’re very forgiving,” says LaGreca. “You can put them in a paper bag in the field, and then prepare the specimen and its label years later.”) Each voucher is “a record of a particular species growing in a particular place at a particular time.” Information about each specimen is also uploaded to an online database, which makes Duke’s collection widely accessible. Sometimes, scientists from other institutions find themselves in need of physical specimens. They’re in luck, because Duke’s lichen collection is “like a library.” The herbarium fields loan requests and trades samples with herbaria at museums and universities across the globe. (“It’s kind of like exchanging Christmas presents,” says LaGreca. “The herbarium community is a very generous community.”)
Duke’s lichen collection functions like a library in some ways, loaning specimens to other scientists and trading specimens with institutions around the world.
Meticulous records of species, whether in databases of lichens or birds or “pickled fish,” are invaluable. They’re useful for investigating trends over time, like tracking the spread of invasive species or changes in species’ geographic distributions due to climate change. For example, some lichen species that were historically recorded on high peaks in North Carolina and elsewhere are “no longer there” thanks to global warming—mountain summits aren’t as cold as they used to be. Similarly, Henry David Thoreau collected flowering plants at Walden Pond more than 150 years ago, and his samples are still providing valuable information. By comparing them to present-day plants in the same location, scientists can see that flowering times have shifted earlier due to global warming. So why does Duke have tens of thousands of dried lichen samples? “It comes down to the reproducibility of science,” LaGreca says. “A big part of the scientific method is being able to reproduce another researcher’s results by following their methodology. By depositing voucher specimens generated from research projects in herbaria like ours, future workers can verify the results” of such research projects. For example, scientists at other institutions will sometimes borrow Duke’s herbarium specimens to verify that “the species identification is what the label says it is.” Online databases and physical species collections like the herbarium at Duke aren’t just useful for scientists today. They’re preserving data that will still be valuable hundreds of years from now.
From shot-putting, to helping conduct two research studies, to being selected for a cardiology conference, meet: Kinsie Huggins. She is from Houston, Texas, currently majoring in Biology and minoring in Psychology with a Pre-Med track here at Duke. With such a simple description, one can already see how bright her future is!
“I want to be a pediatrician and work with kids,” Huggins says. “When I was younger, I lived in Kansas, and in my area, there were no black pediatricians. My mother decided to go far to find one and I really bonded with my pediatrician. One day, I made a pact with her in that I would become a pediatrician too so that I can also inspire other little girls like me of my color and other minority groups.”
Having such a passion to let African-American and minority voices be heard, Huggins is also part of the United Black Athletes, using her shot-put platform to make sure these voices are heard in the athletics department.
And while she may be a top-notch sportswoman, she is also just as impressive when it comes to her studies and research. One of her projects focuses on the field of nephrology – the study of kidneys and kidney disease. She and a pediatric nephrologist are currently working on studying rare kidney diseases and the differences in DNA correlating to these diseases.
Kinsie is also a researcher at GRID (Genomics Race Identity Difference), which studies the sickle cell trait in the NCAA. With the sudden deaths of college athletes from periods of over-exhaustion during conditioning, there has been a rise in attention of sickle cell trait and its impact on athletes. At first, the NCAA implemented a policy that made it mandatory for college athletes to get tested for sickle cell in 2010, but some were wary about the lack of scientific validity in such claims. Now, the NCAA has funded GRID to conduct such research.
The difference of Normal red blood cell and sickle cell (CDC).
“We are analyzing the policy (athletes need to be tested for sickle cell), interviewing athletes in check-ups, and looking at data to see if the policy is working out for athletes and their performance/health,” Huggins explains.
With such an impressive profile, it doesn’t go without saying that Huggins didn’t go unnoticed. The American College of Cardiology (ACC) select high school and college students interested in the field of medicine and have them attend a conference in Washington D.C. to hear about research presentations, groundbreaking results of late-breaking clinical trials, and lectures in the field. Having worked hard, Huggins was selected to be part of the Youth Scholars program from the ACC and was invited to the conference on April 2-4.
Let’s wish Kinsie the best of luck at the conference and on her future research!
